Experimental assessment of a possible microbial priming effect in a humic boreal lake

Dorado-García, Irene; Syväranta, Jari; Devlin, Shawn P.; Medina‐Sánchez, Juan Manuel; Jones, Roger

doi:10.1007/s00027-015-0425-4

Cited by 20 publications

(11 citation statements)

References 54 publications

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“…Moreover, based on DOM characterization (Table ), the natural humic matter from Lake Grosse Fuchskuhle was only little degraded by bacteria, irrespective of LOM addition via Daphnia carcasses. Consequently, and in agreement with previous studies (Bengtsson et al ., ; Catalán et al ., ; Dorado‐García et al ., ), we could not detect any quantitative changes in bacterial ROM degradation when using carcass LOM as a potential primer (Table ).…”

Section: Discussionmentioning

confidence: 98%

“…have been used. Although some authors have found support for ROM priming by more labile organic matter, mainly of algal origin (van Nugteren et al ., ; Guenet et al ., ; Hotchkiss et al ., ; Bianchi et al ., ; Gontikaki et al ., ), others did not reveal any evidence for a positive priming effect (Bengtsson et al ., ; Catalán et al ., ; Dorado‐García et al ., ; Blanchet et al ., ), or even found a negative priming effect (Gontikaki et al ., ) with ROM being decomposed slower in the presence of a labile carbon source. Thus, it appears that the absence or presence of the priming effect may strongly depend on specific environmental or experimental conditions, which may also explain the absence of humic matter degradation in our HD treatments using Daphnia carcasses LOM as the primer.…”

Section: Discussionmentioning

confidence: 99%

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Effects of zooplankton carcasses degradation on freshwater bacterial community composition and implications for carbon cycling

Kolmakova

Gladyshev

Fonvielle

et al. 2018

Environmental Microbiology

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Summary Non‐predatory mortality of zooplankton provides an abundant, yet, little studied source of high quality labile organic matter (LOM) in aquatic ecosystems. Using laboratory microcosms, we followed the decomposition of organic carbon of fresh 13C‐labelled Daphnia carcasses by natural bacterioplankton. The experimental setup comprised blank microcosms, that is, artificial lake water without any organic matter additions (B), and microcosms either amended with natural humic matter (H), fresh Daphnia carcasses (D) or both, that is, humic matter and Daphnia carcasses (HD). Most of the carcass carbon was consumed and respired by the bacterial community within 15 days of incubation. A shift in the bacterial community composition shaped by labile carcass carbon and by humic matter was observed. Nevertheless, we did not observe a quantitative change in humic matter degradation by heterotrophic bacteria in the presence of LOM derived from carcasses. However, carcasses were the main factor driving the bacterial community composition suggesting that the presence of large quantities of dead zooplankton might affect the carbon cycling in aquatic ecosystems. Our results imply that organic matter derived from zooplankton carcasses is efficiently remineralized by a highly specific bacterial community, but does not interfere with the bacterial turnover of more refractory humic matter.

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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Effects of zooplankton carcasses degradation on freshwater bacterial community composition and implications for carbon cycling

Kolmakova

Gladyshev

Fonvielle

et al. 2018

Environmental Microbiology

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“…However, the priming effect has only recently received scrutiny and results of the limited studies to date have been highly discordant. While some studies have reported significant aquatic priming effects using various OC sources (Bianchi et al, ; Guenet et al, ; Hotchkiss et al, ; Steen et al, ), a nearly equal volume of literature argues that priming is not relevant in aquatic systems (Bengtsson et al, ; Blanchet et al, ; Catalán et al, ; Dorado‐García et al, ). This ongoing debate highlights the need for more thorough investigations of the priming effect across multiple aquatic ecosystems.…”

Section: Introductionmentioning

confidence: 99%

An Assessment of Dissolved Organic Carbon Biodegradability and Priming in Blackwater Systems

et al. 2018

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Rivers deliver approximately 260 Tg of dissolved organic carbon (DOC) to the ocean annually, yet there is little evidence of terrigenous DOC (tDOC) in the ocean. While tDOC was historically believed to be stable and resistant to microbial degradation, it has recently been shown that freshwater systems mineralize more tDOC than originally thought. The priming effect is a possible mechanism by which inputs of biolabile DOC enhance the bioavailability of stable DOC components in aquatic systems, resulting in higher rates of microbial remineralization. Here we investigate tDOC biodegradability by conducting bioincubation experiments and utilizing ultrahigh resolution mass spectrometry to characterize the chemical composition of blackwater and leachate dissolved organic matter (DOM) samples. The role of priming in blackwater ecosystems was assessed through the inclusion of bioincubation treatments amended with a variety of simple biolabile OC substrates. Blackwaters lost 6.10 ± 3.85% DOC within 1 month, while leachates lost 38.10 ± 16.74% DOC. There were no significant differences between DOC remineralization in control and primed treatments, indicating that priming is not an important factor in the biodegradation of DOC in blackwater ecosystems. However, the proportion of biodegradable DOC and DOM composition were significantly correlated, mostly driven by the contribution of aliphatic compounds (H/C ≥ 1.5, O/C < 0.9) that were abundant (9.3 ± 5.2%) in leachate DOM. The molecular signature of biodegraded leachate DOM resembled that of stable blackwater DOM, indicating that bioavailable DOM components leached from plant litter are rapidly utilized and stable DOM is exported downstream.

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“…Alternatively, OC stabilization in sediments is tightly linked to organomineral interactions, which provide physical protection from extracellular enzyme activity (Hedges & Keil, ; Hunter et al, ; Rothman & Forney, ), and the strength of these interactions may override any influence of priming. Early investigations of priming effects in aquatic systems have been inconclusive, with evidence both for (Dorado‐García et al, ) and against (Bengtsson et al, ; Catalán et al, ) priming mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Carbon Inputs From Riparian Vegetation Limit Oxidation of Physically Bound Organic Carbon Via Biochemical and Thermodynamic Processes

et al. 2017

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In light of increasing terrestrial carbon (C) transport across aquatic boundaries, the mechanisms governing organic carbon (OC) oxidation along terrestrial‐aquatic interfaces are crucial to future climate predictions. Here we investigate the biochemistry, metabolic pathways, and thermodynamics corresponding to OC oxidation in the Columbia River corridor using ultrahigh‐resolution C characterization. We leverage natural vegetative differences to encompass variation in terrestrial C inputs. Our results suggest that decreases in terrestrial C deposition associated with diminished riparian vegetation induce oxidation of physically bound OC. We also find that contrasting metabolic pathways oxidize OC in the presence and absence of vegetation and—in direct conflict with the “priming” concept—that inputs of water‐soluble and thermodynamically favorable terrestrial OC protect bound‐OC from oxidation. In both environments, the most thermodynamically favorable compounds appear to be preferentially oxidized regardless of which OC pool microbiomes metabolize. In turn, we suggest that the extent of riparian vegetation causes sediment microbiomes to locally adapt to oxidize a particular pool of OC but that common thermodynamic principles govern the oxidation of each pool (i.e., water‐soluble or physically bound). Finally, we propose a mechanistic conceptualization of OC oxidation along terrestrial‐aquatic interfaces that can be used to model heterogeneous patterns of OC loss under changing land cover distributions.

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Experimental assessment of a possible microbial priming effect in a humic boreal lake

Cited by 20 publications

References 54 publications

Effects of zooplankton carcasses degradation on freshwater bacterial community composition and implications for carbon cycling

Effects of zooplankton carcasses degradation on freshwater bacterial community composition and implications for carbon cycling

An Assessment of Dissolved Organic Carbon Biodegradability and Priming in Blackwater Systems

Carbon Inputs From Riparian Vegetation Limit Oxidation of Physically Bound Organic Carbon Via Biochemical and Thermodynamic Processes

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